Concatenate text and checkbox data entered in userform

Hi,

I'm new to VBA, but trying to learn quickly. Attached is a userform I have created but I'm struggling with the required code.
The code I am looking for will concatenate the text from job number and BU with selections made in region and head code check boxes and put in column A and description entered put in column B.
For example , if JOP0004E is typed in job number field and BU is 20 and NSW, VIC, QLD are checked and 62, 63 are checked the following combinations would be recorded in column A (column B description is always the same)
2022EXP62JOP0004E
2022EXP63JOP0004E
3022EXP62JOP0004E
3022EXP63JOP0004E
4022EXP62JOP0004E
4022EXP63JOP0004E

The leading two numbers relate to region and are as follows:
NATIONAL = 10
NSW = 20
VIC = 30
QLD = 40
SA = 50
WA = 60

There is only one exception rule which I would like included. If NATIONAL is checked, it doesn't matter what head codes are checked, it will only setup head code 64 eg
1022EXP64JOP0004E

If any of this doesn't make sense I'm more than happy to explain further. If someone can just get me started with the code, I'm happy to put in the various combinations if this is what's needed.

Many thanks for your assistance.